From 5af18773bffe99deea9fa2defc5c05475cdf4161 Mon Sep 17 00:00:00 2001
From: Pokechu22 <Pokechu022@gmail.com>
Date: Wed, 1 Dec 2021 18:51:21 -0800
Subject: [PATCH] FifoPlayer: Clear EFB before starting playback

This fixes the bad rendering on the first frame when using the software renderer: the software renderer's Z buffer started out at 0, but most games clear it to 0xffffff instead; this means that things don't render correctly except for in the regions where the screen was cleared by an EFB copy earlier in the frame.
---
 Source/Core/Core/FifoPlayer/FifoPlayer.cpp | 41 ++++++++++++++++++++++
 Source/Core/Core/FifoPlayer/FifoPlayer.h   |  1 +
 2 files changed, 42 insertions(+)

diff --git a/Source/Core/Core/FifoPlayer/FifoPlayer.cpp b/Source/Core/Core/FifoPlayer/FifoPlayer.cpp
index a1a56dffc8..47b9ac2f87 100644
--- a/Source/Core/Core/FifoPlayer/FifoPlayer.cpp
+++ b/Source/Core/Core/FifoPlayer/FifoPlayer.cpp
@@ -25,6 +25,7 @@
 #include "Core/PowerPC/PowerPC.h"
 #include "VideoCommon/BPMemory.h"
 #include "VideoCommon/CommandProcessor.h"
+#include "VideoCommon/VideoCommon.h"
 
 // We need to include TextureDecoder.h for the texMem array.
 // TODO: Move texMem somewhere else so this isn't an issue.
@@ -452,6 +453,45 @@ void FifoPlayer::SetupFifo()
   WriteCP(CommandProcessor::CTRL_REGISTER, 17);  // enable read & GP link
 }
 
+void FifoPlayer::ClearEfb()
+{
+  // Trigger a bogus EFB copy to clear the screen
+  // The target address is 0, and there shouldn't be anything there,
+  // but even if there is it should be loaded in by LoadTextureMemory afterwards
+  X10Y10 tl;
+  tl.x = 0;
+  tl.y = 0;
+  LoadBPReg(BPMEM_EFB_TL, tl.hex);
+  X10Y10 wh;
+  wh.x = EFB_WIDTH - 1;
+  wh.y = EFB_HEIGHT - 1;
+  LoadBPReg(BPMEM_EFB_WH, wh.hex);
+  LoadBPReg(BPMEM_MIPMAP_STRIDE, 0x140);
+  // The clear color and Z value have already been loaded via LoadRegisters()
+  LoadBPReg(BPMEM_EFB_ADDR, 0);
+  UPE_Copy copy;
+  copy.clamp_top = false;
+  copy.clamp_bottom = false;
+  copy.yuv = false;
+  copy.target_pixel_format = static_cast<u32>(EFBCopyFormat::RGBA8) << 1;
+  copy.gamma = 0;
+  copy.half_scale = false;
+  copy.scale_invert = false;
+  copy.clear = true;
+  copy.frame_to_field = FrameToField::Progressive;
+  copy.copy_to_xfb = false;
+  copy.intensity_fmt = false;
+  copy.auto_conv = false;
+  LoadBPReg(BPMEM_TRIGGER_EFB_COPY, copy.Hex);
+  // Restore existing data - this only works at the start of the fifolog.
+  // In practice most fifologs probably explicitly specify the size each time, but this is still
+  // probably a good idea.
+  LoadBPReg(BPMEM_EFB_TL, m_File->GetBPMem()[BPMEM_EFB_TL]);
+  LoadBPReg(BPMEM_EFB_WH, m_File->GetBPMem()[BPMEM_EFB_WH]);
+  LoadBPReg(BPMEM_MIPMAP_STRIDE, m_File->GetBPMem()[BPMEM_MIPMAP_STRIDE]);
+  LoadBPReg(BPMEM_EFB_ADDR, m_File->GetBPMem()[BPMEM_EFB_ADDR]);
+}
+
 void FifoPlayer::LoadMemory()
 {
   UReg_MSR newMSR;
@@ -469,6 +509,7 @@ void FifoPlayer::LoadMemory()
 
   SetupFifo();
   LoadRegisters();
+  ClearEfb();
   LoadTextureMemory();
   FlushWGP();
 }
diff --git a/Source/Core/Core/FifoPlayer/FifoPlayer.h b/Source/Core/Core/FifoPlayer/FifoPlayer.h
index f2444e56d2..01ce07c4a0 100644
--- a/Source/Core/Core/FifoPlayer/FifoPlayer.h
+++ b/Source/Core/Core/FifoPlayer/FifoPlayer.h
@@ -123,6 +123,7 @@ private:
   void LoadMemory();
   void LoadRegisters();
   void LoadTextureMemory();
+  void ClearEfb();
 
   void WriteCP(u32 address, u16 value);
   void WritePI(u32 address, u32 value);